Electrical insulator



Dec. 6, 1927.

A. M. TROGNER ELECTRICAL INSULATOR FiIed Feb. 17

JTTORNEY m m m N J.

Patented Dec. 6, 1927.-

UNITED STATES ARTHUR M.

1,651,783 PATENT OFFICE.

INQ, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

ELECTRICAL INSULATOR My invention relates broadly to electrical insulators and more particularly to an insulator for high frequency currents.

One of the objects of my invention is to provide a construction of cylindrical insulator in \VlllClFthQ electrical capacity between opposite ends of the insulator may be considerably reduced and the high frequency insulation considerably increased over that. heretofore obtainable.

Another object ofmy invention is to provide a construction of insulator for high frequency currents in which the insulator may be assembled in a simplified manner for manufacture of insulators on a quantity of production scale inexpensively.

Another object of my invention is to provide a construction of insulator wherein a hollow tubular insulating member is provided with recessed end members secured in position with respect to the insulator in such manner that the electrostatic capacity between end members is considerably reduced, -while the di-electric strength at high frequency is considerably increased.

My invention will be more clearly understood with reference to the following specification and the accompanying drawing, in which: Figure 1 illustrates in a plan view :so the assembly of a piezo-electric crystal apparatus illustrating one of the applications of the electrical insulator of my invention; Fig. 2 is a side elevation of a piezo-electric crystal apparatus illustrating the electrical insulator construction of my invention shown in cross-section; Fig. 3 is a view illustrating one of the methods of assembly which if employ in the manufacture of the electrical insulator; and Fig. 4 illustrates the completed electrical insulator ready for installation upon high frequency electrical apparatus. j

Referring to the drawing in detail, I have illustrated my invention as applied to high frequency circuits in which piezo-electric crystals are employed where the piezoelectric crystal apparatus 1 is supported upon a base plate 2 with terminals 3 and 4 protruding from the piezoelectric crystal apparatus 1 providing connections to external electrical circuits.

The electrical insulator of my invention is illustrated as supported upon the plate member 2 and secured thereto by means of a screw member 5 which is screw threaded into the metallic end piece 6. The metallic end piece 6 is provided with an annular groove 7 into'which the end of the insulated cylindrical member 8 snugly fits. The insulated cylindrical member 8 is in the form of a vertical standard of hollow insulating material in the form of atube. The hollow insulating tube 8 has a very .small part of its ends exposed to the cylindrical members 6 and 9, each of the cylindrical members 6 and 9 being grooved as represented at 7 and 10 to permit the entrance of the ends of the hollow tubular member 8 therein. The hollow tubular member 8 must be cemented in the annular grooves 7 and 10 after the assembly of the several parts on a screw threaded rod member 11 as represented in Fig. 3 where the rod member 11' engages the screw threads 12 and 14 in the end members 9 and 6 respectively. The use of a hollow tube or insulating member 8 permits TROGNER, 0F TFAKOMA PARK, MARYLAND, ASSIGNOR TO WIRED RADIQ,

a very simple assembly process to be followed and insures concentricity of the aper- Itures 12 and 14. After the setting of the cement, the rod member 11 may be removed and the screw threads in the end members 6 and 9 employed as a means of securing the insulating member in a: vertical position by .the' engagement of screw member 5 with the screw threads 14 in end member 6 by the engagement of screw device 15 in the screw threads 12 of end member 9 for positioning the contact member 16 with respect to the protruding contact 4.

The electrical insulator of my invention has a distinctive advantage over insulating material in the form of a solid rod as the creepage length between the metallic end pieces may be much greater, in the insulator of hollow tubular construction than in an insulator of solid construction with metal caps fitting over the ends. The reason for this will be readily apparent when the physical construction is considered where it is necessary to establish a rigid mechanical connection between end members and the insulated body portion. In the case of the hollow tubular member, the end members grip both the inside and the outside of the insulated body portion end so the/distance over which the metallic end member extends with respect to the insulated body portion need not be as great as the distance of overlap which will be necessary in the case of the attachment of an end member to a solid rod of insulated material. The ease of assembly of insulators constructed in accordance with my invention further increases the desirabil ity of the insulator construction of my invention.

The insulator in accordance to the specification herein has proven to be highly successful in operation and many applications in high frequency electrical apparatus have been found for the device of my invention.

lVhat I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. An electrical insulator comprising a tubular insulating member and a. pair of end pieces, each of said end pieces being provided with an annular recess therein for receiving the ends of said tubular member, said end pieces being screw threaded for enabling a tie member to be passed between the end pieces for securing said end pieces in position during the process of assembly of said insulator and providing means for the attachment of supporting means at each end of said insulator subsequent to the re moval of said screw threaded member.

2. An electrical insulator comprising a tubular insulating member, a pair of cylindrical end members each having an annular recess therein arranged to receive the ends of said tubular member, each of said cylindrical end members being screw threaded at their centers for receiving a screw threaded tie rod therebetween for securing said cylindrical end members in position with respect to said tubular member during the process of assembly and for providing attachment means to said end members subsequent to the removal of said screw threaded tie rod.

ARTHUR M. TROGNER. 

